Chromium Speciation and Distribution in the Great Lakes

Abstract

A technique is described for selectively measuring the forms of chromium in freshwater samples, with detection limits of 21 ng L-1 for Cr(III), 4 ng L-1 for Cr(VI), and 8 ng L-1 for colloidal/organic Cr. Recovery of the Cr(VI) and Cr(III) spikes were consistently >90%, but only about 70% for the added organic Cr. When the method was applied to samples from Lake Ontario, it was found that Cr(VI) made up 75-85% of the dissolved Cr and that Cr(III) was consistently below the analytical detection limit. About 10% of the dissolved Cr was in the colloidal/organic form. Average concentrations of total dissolved Cr in the epilimnetic waters were found to be 69 ng L-1 in Lake Superior, 136 ng L-1 in Lake Erie, and 351 ng L-1 in Lake Ontario. The increasing concentration of Cr down the Great Lakes watershed reflects the conservative geochemical behaviour of Cr(VI) and the increasing input of Cr from industrial and municipal sources

The effect of organic compounds in the oxidation kinetics of Cr(III) by H2O2

“…Indirect evidence supports the existence of organoCr(III) species in aquatic systems and soil solutions (Nakayama et al, 1981;Beaubleu et al, 1994;Puzon et al, 2005Puzon et al, , 2008, but unfortunately no direct measurements of these species have been determined under natural environmental conditions. Aha and Bha have been often used as model compounds for hydroxamic siderophores (Abu-Dari et al, 1979;Farkas et al, 1998;Boukhalfa and Crumbliss, 2001).…”

“…Despite the relevant role played by organo-Cr(III) species, which has been highlighted in a number of field and laboratory studies (Nakayama et al, 1981;Beaubleu et al, 1994;Ś wietlik, 1998;Srivastava et al, 1999;Puzon et al, 2008), the influence of complexing agents on Cr(III)/Cr(VI) interconversions has not been fully investigated. Mabbett et al (2002) proved that bioreduction of Cr(VI) by Desulfovibrio vulgaris ATCC 29579 under anaerobic conditions occurred only in the presence of ligands or chelating agents and found a positive correlation of the stimulatory effects of organics on the rates with the strength of Cr(III) complexes they formed.…”

The Monitoring of Cr(III) and Cr(VI) in Natural Water and Synthetic Solutions: An Assessment of the Performance of the Dgt and Dpc Methods

“…Cathodic stripping voltammetry (Galimowski et al, 1985;Korolczuk, 2000) and the Sephadex ion exchange method (Hiraide and Mizuike, 1989;Beaubien et al, 1994) were also tested but were not used on a routine basis as they are more time consuming and require a mobile laboratory. Also, our laboratory experiments with natural samples indicated a very low recovery by Sephadex of the colloidal Cr fraction.…”

Cr-(III)-organic compounds treatment causes genotoxicity and changes in DNA and protein level in Saccharomyces cerevisiae

“…Organo-Cr(III) species enhances the mobility of chromium which in turn, increase the risk of Cr(III) migration in groundwater (Puzon et al 2005(Puzon et al , 2008 particularly at Cr(VI) contaminated sites. Despite the relevant role played by organo-Cr(III) species, which has been highlighted in a number of field and laboratory studies (Nakayama et al 1981;Beaubleu et al 1994;Ś wietlik 1998;Srivastava et al 1999;Puzon et al 2008), the influence of complexing agents on Cr(III)/Cr(VI) interconversions has not yet been fully investigated. The instantaneous formation of stable Cr-(III)-organic complexes suggests that Cr-(III)-organic complexes are rather common, likely representing an integral part of the natural biogeochemical cycle of chromium.…”